(1) Field of the Invention
The present invention relates to a fire transmission prevention system which prevents the spread of smoke and fire from floor to floor in a structure through the branch drainage system. In particular, the present invention relates to a fire transmission prevention system which has a firestop coupling positioned between the floors in the drainage system and an air vent positioned in the branch drainage system above the highest trap in the branch drainage system.
(2) Description of the Related Art
To function properly, a branch drainage system must be provided with an air intake such as an air admittance valve or vent to prevent the formation of a vacuum in the drainage pipes. If the vacuum is formed and becomes too large, the water in the traps would be drawn out of the traps, whereafter, the sewer gas would be able to move up through the pipes to the surrounding rooms.
The related art has shown various types of air admittance valves for use on a stack pipe of a drainage system. The valves act to close off the pipe when there is at least atmospheric pressure in the pipe and to open up the pipe to admit air to the pipe to equalize the pressure in the pipe upon the occurrence of less-than-atmospheric pressure. Illustrative are U.S. Pat. Nos. Re. 35,532 to Duren; 3,605,132 to Lineback; 3,923,081 to Persson; 4,232,706 to Ericson; 4,436,107 to Persson; 4,535,807 to Ericson; 4,545,398 to van Olst; 4,556,084 to Frawley; 4,867,802 to Earl; 4,962,548 to van Deventer et al; 4,974,632 to Ericson and 5,048,562 to Frawley.
Also of some interest are U.S. Pat. Nos. 2,928,413 to Hansen; 3,815,629 to Oberholtzer and 4,712,574 to Perrott. Hansen describes a valve for relieving internal pressures and vacuums that tend to occur in storage tanks. Oberholtzer describes a sewer valve which prevents the backing up of water in plugged sewer lines by releasing the backed up sewage water to outside the structure without venting sewer gases to the atmosphere. Perrott describes a vacuum breaking valve for use in pressurized fluid supply lines to prevent back siphoning or flow reversal whenever an operational variant causes a vacuum to be produced in the supply system.
Only of minimal interest are U.S. Pat. Nos. 4,643,221 to Parker and 5,117,860 to Horner, Jr. which describe vacuum check valves for use in a vacuum supply line as a control for a vacuum suspended brake booster supply.
The related art has also shown various types of firestops to prevent the spread of smoke and fire through the pipes of a waste or drainage system. Illustrative are my U.S. Pat. Nos. 4,583,565; 4,638,829 and 4,724,858 which describe firestop fittings particularly adapted to prevent the spread of smoke and fire between floors in a multi-story structure by plugging off any potential fire path through a vertical pipe mounted between the floors. These patents describe an assembly where a non-flammable plug is released by heat less than required for heat destruction of a plastic coupling mounted in a floor. Upon being released, the plug moves into and seals an iron fitting mounted inside of the plastic coupling to serve as a non-flammable barrier through the iron fitting. This retards the spread of fire through the plastic coupling by depriving the inside of the coupling of oxygen.
In addition, my U.S. Pat. No. 5,183,070 describes a similar firestop fitting having a movable plug for plugging off a vertical pipe mounted between fire rated floor members. Further, my U.S. Pat. No. 5,127,425 describes a firestop fitting having a movable plug for plugging off a horizontal pipe mounted between vertical, fire rated wall members. Both of these inventions are particularly adapted to prevent the spread of smoke and fire through the pipe of a drainage system by plugging off the inside of the pipe.
The art also shows couplings which prevent the spread of smoke between floors; particularly, concrete floors. Illustrative are my U.S. Pat. Nos. 4,261,598; 4,623,170; 5,035,097; 5,040,351 and 5,293,724 which show couplings for mounting in partitions such as concrete floors or walls which are mounted to prevent smoke from moving between the couplings and the partition.
There remains the need for a fire transmission prevention system which uses an assortment of firestop, air vents and couplings mounted in a branch drainage system to prevent the transmission of fire and smoke from floor to floor in a structure by way of the drainage system.